Behind the scenes, it’s a different story; your customers may not expect or understand.

Historically, car steering systems were hydraulic. They used a pump to move fluid to the power assist of a steering gear or rack and pinion. This pump was driven by the vehicle’s engine, usually via a belt. It was just assist, and the driver was moving the wheels. Today, the driver still has control of the vehicle, but the assistance comes from an electrical source.

To understand the basic EPAS system, it is important to know the three basic types.

The first is a column mount system – as you might expect, this type mounts the assist assembly in the column. The column-mounted EPS uses an electric motor on the steering shaft to add assistance when turning the steering wheel. This design has the advantage of keeping electrical components inside the vehicle and out of the elements. Unfortunately, mechanical repairs to these components may require disassembly of the dashboard and other systems.

The second type of system is a hydraulic power assist type. The basic design is similar to belt driven hydraulic power steering pump systems, but the big difference is that it is not driven by vehicle engine power – it uses an electric motor to drive the steering turbine. the pump.

The final type of assist is an electric rack and pinion system, which comes in four basic categories. Concentric or axial driven units incorporate the motor in the rack and the armature drives a screw shaft which moves the rack. The belt-driven style uses an electric motor and a belt to drive the motion. The latter two use motor driven pinions, driving either the rack input shaft on a single pinion design or the rack bar shaft on a dual pinion.

No matter what type of system your customer has concerns with, chances are your investigation will involve sensors at some point. The first sensor is the steering wheel position sensor. The system must know in which direction the driver is steering the vehicle. The system uses the steering wheel position sensor to read the intended direction.

EPAS systems use the speed sensors anti-lock braking system data to indicate wheel rotation speed.

There is a torque sensor in these systems that tells the steering to help how much torque a driver is putting on the steering wheel. The combined information from the speed sensors and the torque sensor allows the system to calculate the level of assistance to provide to the steering system.

EPAS systems can also use a dynamic sensor. This sensor indicates the movement of the vehicle and the direction of travel. This allows the vehicle to use braking, throttle and, in some cases, low effort steering assist to correct for differences in steering direction and actual direction of travel.

More complex systems can present your customers with higher repair bills than expected. Your understanding and explanation of how the power steering system works will help eliminate their uncertainty.

This video is sponsored by The Group Training Academy.